Method and apparatus for cold drawing metal tubes

ABSTRACT

A plurality of ultra-sonic transducers are fitted on one or more flanges, the transducers being at right angles to an elongated transmitting body which combines the vibrating energy of respective flanges and changes the direction of the vibrations by 90*. The longitudinal vibration of the transmitting body is applied to a plug of a tube drawing machine. The vibrating amplitude of the system is detected and deviations from a predetermined set value are corrected.

United States Patent Isobe et al.

[ 1 Apr. 25, 1972 METHOD AND APPARATUS FOR COLD DRAWING METAL TUBES Inventors: Kenjiro Isobe, Kawasaki; Hitoshi Tsuji, Kawasaki; Shigeo Kawahata, Kawasaki; Eiji Mori; Katsuhiko Ito, both of Tokyo,

all of Japan Assignee: Nippon Kokan Kabushiki Kaisha Filed: Mar. 9, 1970 Appl. No.: 17,732

Foreign Application Priority Data Sept. 16, 1969 Japan ..44/72990 U.S. Cl ..72/8, 72/56, 72/283 Int. Cl. l ..B2lc 3/16 Field of Search... ..72/56, 282, 8, 9, 283;

References Cited UNITED STATES PATENTS 3,002,614 10/1961 Jones ..72/56 3,209,573 10/1965 Boyd et al.. 3,233,012 2/1966 Bodine, Jr ..72/56 Primary Examiner-Richard J. Herbst Att0rneyFlynn and Frishauf [5 7] ABSTRACT A plurality of ultra-sonic transducers are fitted on one or more flanges, the transducers being at right angles to an elongated transmitting body which combines the vibrating energy of respective flanges and changes the direction of the vibrations by 90. The longitudinal vibration of the transmitting body is applied to a plug of a tube drawing machine. The vibrating amplitude of the system is detected and deviations from a predetermined set value are corrected.

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PATENTEDAPR 2 5 I972 SHEET 8 [1F 6 METHOD AND APPARATUS FOR COLD DRAWING METAL TUBES BACKGROUND OF THE INVENTION This invention relates to novel method and apparatus for drawing metal tubes and more particularly to method and ap paratus capable of providing the amount of ultra-sonic vibrating energy required for cold drawing metal tubes of any material and dimension.

The method of 'manufacturing metal tubes by cold drawing is advantageous in providing high quality tubes because it can provide tubes of high'dimensional accuracy and good surface finish. On the other hand, an increase in the deformation resistance encountered at the time of drawing requires large drawing power. Accordingly, this method is inevitable to decrease efficiency and increase cost of manufacturing. Efforts have been concentrated to thedevelopment of improved cold drawing processes.

According to one most prospectivemethod, use is made of vibrations of ultra-sonic waves. This processgreatly reduces the deformation resistance during drawing and hence increases the drawing speed. However, due to the limit of the available vibrating energy of ultra-sonic waves, application of this method is limited to tubes of thin wall or small'diameter. It is presumed that this disadvantage is caused by the fact that the ultra-sonic wave transducer is coupled in series with the tube drawing mandrel. Even when the vibration is amplified by means of a horn, the vibrating energy available from a single transducer is limited by the material and construction thereof.

SUMMARY OF THE'INVENTION This inventioncontemplates elimination of above described difficulties by providing a novel method and apparatus for deriving ultra-sonic vibrating energy of ultra-sonic waves of any desired magnitude regardless of the material and'dimension of the metal tubes.

According to this invention, a plurality of relatively small transducers are titted on the periphery of a flange or disc, the diameter of the flange being selected in. accordance withthe vibrating frequency. Thus, the 'flangeresonatesto provide a maximum resonanceenergy corresponding to the resultant of the energies of the individual transducers fitted on the periphery of the flange. Bycoupling a suitable transmitting member to the flange at substantially right angles to the flange, it is possible to readily change by90 the direction of the ultra-sonic resonance oscillations of the flanger-By. increasingthe number of flanges the resultant vibrating. energy transmitted through the transmitting body will be increased. Thus, by coupling atube drawing mandrel .to one end of the transmitting body, the vibration transmitted to the mandrel andthe plug carried thereby will be readily controlled bythe number of flanges employed and the number of transducers fitted thereto.

Thus, byproviding apluralityof relatively small ultra-sonic transducers arranged in one or more stages, it isxpossibleto provide stable vibrating energy of any magnitude desired for any particular material and ,dimensionof the metal tube to be drawn.

The present invention makes use of vibration devices dis closed in US. Pat. application, Ser. No. 86,928, assigned to the same assignec as the. present application.

By virtue of this invention, the deformation resistance encountered during the cold draw operation of metal tubes is greatly decreased, thus increasing the drawing power and efficiency and hence decreasing manufacturing costs.

The method and apparatus of this invention can be applied to cold drawing process of metal tubes of any material and dimension which have been used commercially.

The transducers employed in this invention may be of the electrostrictive or magnetostrictive type. However, the electrostrictive type is preferred.

BRIEF DESCRIPTION OF THE DRAWING The invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 shows a side elevation of a metal tube drawing apparatus embodying this invention and utilizing the vibrating energy of ultra-sonic waves;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1;

FIG. 3 is partial sectional view to illustrate the manner of drawing a metal tube;

FIG. 4 shows a cross-section taken along a line IV IV in FIG. 1;

FIG. 5 is a side view, partly in section, of a supporting device of a converter of the ultra-sonic wave vibration;

FIG. 6 is a top plan view of the supporting device shown in FIG; 5;

FIG. 7 is a sectional view taken along a line VII VII in FIG. 6;

FIG. 8 is a sectional view taken along a line VIII VIII in FIG. 6;

FIG. 9 is a sectional view taken along a'line IX IX in FIG. 6;

FIG. 10 shows a coupling between a converter of the vibrating direction of the ultrasonic waves and the manner of supporting a plug;

FIG. 11 shows a coupling between the converter of the vibrating direction of the ultra-sonic waves and a mandrel bar;

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the accompanying drawing, FIG. 11 shows one example of a transmittingmechanism of ultra-sonic vibrating energy provided with a pluralityofultra-sonic transducers of the electrostrictive or magnetostrictive type. In this example, there are shown six flanges of discs 51A,. 51B, 51C, 51D, 51E and SIP for supporting transducers. These flanges are formed integrally with a transmitting body50 for the vibrating energy and are disposed right angles thereto. In this case, each flange is a dodecagon with 12 transducers 60se cured to respective sides thereof. In this'mechanism, it is necessary to select the diameter of each flange to be equal to M2, where A represents the wavelength of the ultra-sonicwave generated by the transducers and the spacing between adjacent flangesto be equal also to M2. Suitable supporting means 52A, 52B, 52C and 52D are interposed between suitable pairs of flanges. Spacings between respective supporting means and flanges are also selected to be equal to M2.

Transducers 60 may be secured to the flanges by any suitable means such as screws or welding. Fig.'ll shows a construction for screw connection. For this purpose, each side of the flanges is provided with threaded openings. A suitable vibration detecting pickup 61*may be secured to one end of the transmittingbody to readily determine the vibrating condition of the entire system.

Vibrations created in the radial direction in the flanges as shown by an arrow 62 by the energization of respective transducers are converted into axial vibration of the transmitting body 50 as shown by an arrow 63. As has been described hereinabove, such axial vibrating energy is theresultant of the radial vibrating energies of respective flanges. As shown in FIGS. 11 and l2,a mandrel 70 and a plug 71 are connected to the other end of the vibration transmitting body 50, or the leftmm. Where the length of the mandrel 70 is selected to be equal to an integer multiple of one half of the wavelength (M2 X n), the plug will be on the vibrating crest, thus eliminating the loss of the vibrating energy. The joint between the transmitting body 50 and mandrel 70 should be made to correspond to the vibrating crest. To this end coupling means 53 and 72 are provided respectively spaced apart M4 from the abutting surface 55, said coupling means being connected together by bolts 54. A suitable vibrating attenuator 56 and amplifier 79 may be provided for the transmitting body a shown in FIGS. 11 and 12.

In applying the transmitting body for ultra-sonic wave vibrations shown in FIG. 11, 12 and 13 to a commercial drawing apparatus of metal tubes, more detailed considerations are required. FIGS. 1' through 10 show an example of a tube drawing machine designed for such a vibration generating device.

More particularly, the vibration transmitting body shown in FIG. 11 is incorporated into a housing 1, shown in FIGS. 1 and 2. As shown in FIGS. 5 and 6, the housing 1 is a frame structure comprising longitudinal C shaped structural steel elements 25A and 25B and transverse ribs 26A, 26B, 26C, 26D, 26E and 26F, to which bearings 2B, 2C, 2D and 2E for supporting supporting members 52A, 52B, 52C and 52D of the transmitting body 50 shown in FIG. 11 are secured by bolts 17 and clamping members 3C, 3D, 3E (clamping member 38 is not seen in the drawing) which are clamped by bolts 22 whereby to restrain free movement of the upper portion of the transmitting body 50. As shown in FIGS. 9 and 5, wheels 8A, 8B and 8C (not shown) and 8D are provided for ribs 26D and 268, respectively, to support the transmitting body 50 and housing 1. These wheels are rotated by shafts 9 secured to slidable plates 10A, 10B, 10C and 10D (10D is not seen in the drawing) and are adjusted in the vertical direction by adjusting screws 11A, 11B, 11C and 11D (11D is not seen in the drawing) for aligning axes of the transmitting body 50 and a die 80. Wheels 8A, 8B, 8C and 8D are mounted on rails 106 to permit horizontal movement of the housing 1. A stop 13 including rubber cushions 14 is mounted on bearing 2D secured to rib 26D, as shown in FIG. 6, to stop rearward movement of the transmitting body 50. Further, as'shown in FIGS. 5, 8 and 9, safety covers 15, 16 and 24 are provided for the transmitting body 50.

The coupling between the vibration transmitting body 50 and the mandrel bar is shown generally in FIGS. 5 and 6 and in detail in FIGS. 7 and 10. Thus, as described hereinabove, the coupling comprises flanges 72 and 53 which are connected together by bolts 54. Inclined shoulder 79 provides an amplifying function for the vibrating energy as above described and in addition functions to receive the tensile strength of the mandrel. As shown in FIG. 10, the shoulder 79 of the mandrel bar 70 is supported by a ring 5 which is fitted on the mandrel bar 70 and supported by members 4A and 4B, thus receiving the tensile strength of the mandrel bar created by the drawing operation of the metal tubes by rib 26A of the housing 1. This construction relieves the coupling between the transmitting body and the mandrel bar from any external force that tends to separate them. The opposite end of the housing 1 is stably held by a universal coupling mechanism 6 and 7 secured to rib 26F.

The entire tube drawing machine equipped with the housing 1 containing the above-described transmitting body for the ultra-sonic vibrating energy is shown in FIGS. 1 and 2, while a detail of a portion thereof is shown in FIGS. 3 and 4. With reference first to the mechanism to the rear of housing 1, the universal coupling 6 and 7 is connected to a rear mandrel bar 73 through a load detector 74 for measuring the plugging power, the rear mandrel bar 73 being connected to an air cylinder 76 via a supporting member 75. The air cylinder 76 is slidably moved in the horizontal direction by a screw threaded rod 78 driven by an electric motor 77 to adjust the relative position between a die 80 and a plug 71. Portions of the mandrel bar 70 before die 80 and supported by supporting members 4A, 4B and 5 fixed to rib 26A are contained in a trough 102A as shown in FIG. 4. As best shown in FIG. 3, die is supported by a die holder 101 through a ring shaped spacer 81 to define an annular die passage 81 between die 80 and plug 71. Thus a tube 130 is drawn through this die passage by means of a pulling device 110. It is advantageous to form the die holder 101 as an integral part of a draw head 100.

For drawing metal tubes it is necessary to provide a suitable control device for ultra-sonic transducers. In the example shown in FIG. 2, the frequency of the ultra-sonic transducer 121 is controlled by a control device 122 responsive to a signal 125 detected by pickup 61 already described in connection with FIG. 11. Should the detected vibrating speed (or frequent) deviate from a set value (60 cm/sec. for instance) by the change in the draw resistance of the metal tube or the load of the machine, the control device 122 immediately operates to restore the vibrating speed or frequency to the set value. The output from the control 122 is amplified by an amplifier 123 and the amplified signal 124 is applied to respective transducers. Thus the ultra-sonic vibrating energy with its vibrating speed or frequency maintained at a fixed set value is imparted to the plug through the transmitting body in a manner already described.

Upon completion of the drawing operation of one metal tube, rear mandrel bar 73, housing 1, mandrel bar 70 and plug 71, which are interconnected, are withdrawn by motor 77 through threaded rod 78 and air cylinder 76. Then, the supporting trough 102A for mandrel bar 70 is raised by lifting members 105A, 1058 and 105C while at the same time shafts 104A, 1048 and 104C are rotated by the operation of an air cylinder 103 to lower another supporting trough 1028 to the operating position, which is supplied with a next blank tube to be drawn, thus preparing for the next drawing cycle.

One example of data regarding operating conditions and results of the method and apparatus described above is as follows:

Mntorlal:

ASTM A-312 (stainless stoll tube.) ASTM A-83 (Carbon steel tube). Vibrating frequency =20 kIIz.

ASTM

Blank tube, 1nm .{Outer diameteL 34. 0 34. 0 42. 0 Wall thickness .2. 00 3. 00 4. 50 Finished tube, nrm Outer diarnet 25. 4 25. 4 36. 0 Wall tlricknes 2. 2O 2. 20 3. 0 gercentqgelpf surface reduciion, percent... 45. 0 45.0 41. 0 ower o u ra-sonie wave \v 3-5 3-5 4-6 Energy for drawing tubes: gll ubu speed, rn./min 2 .9 1. .9 23. 9 ower, t 15 10 16 As can be clearly noted from this table, the percentage of surface reduction, power, and the energy for drawing the tube are superior to those of the prior tube drawing process described above.

What is claimed is:

1. A method of cold drawing metal tubes by applying vibrating energy to a plug comprising the steps of:

drawing a tube through a die and over a plug which is cooperatively located with respect to said die; coupling said plug to a source of vibrations to thereby form a vibrating system;

generating in said source of vibrations vibratory energy directed substantially perpendicular to the direction of drawing said tube and changing the direction of said vibrating energy by to direct said energy in the direction of drawing said tube;

measuring the vibrating amplitude of said vibrating system;

generating a correction signal when said vibrating amplitude deviates from a predetermined value required for operation. and

coupling said correction signal to said source of vibrations to change the vibrating amplitude of said vibrating system to said predetermined value required for operation.

2. The method of claim 1 wherein said source of vibrations includes at least one vibration transducer generating vibrational energy in said direction substantially perpendicular to the direction of drawing said plug, and wherein said correction signal is coupled to said at least one vibration transducer to change the vibrating frequency thereof. t

3. The method of claim 2 wherein said source vibrations includes a plurality of said transducers spaced around the periphery of a disc-shaped member which has its plane substantially perpendicular to said direction of drawing.

4. The method of claim 1 including the step of measuring the plug load, and adjusting the relative positions of said die and plug as a function of said plug load.

5. Apparatus for cold drawing metal tubes comprising:

a die through which a tube is drawn;

a plug around which said tube is drawn, said plug cooperating with said die;

a vibration source;

rod-like means coupling said vibration source to said plug,

the longitudinal axis of said rod-like means being substantially in the direction of drawing of said tube, said rod-like means; said plug and said vibration source comprising a vibrating system;

said vibration source comprising at least one vibration transducer generating vibratory energy in a direction substantially perpendicular to the longitudinal axis of said rod-like means, and means for changing the direction of said vibratory energy by 90, whereby the resulting vibratory energy is in the direction of the longitudinal axis of said rod'like means;

means coupled to said vibrating system for measuring the amplitude of vibrations thereof; and

means coupled to said at least one transducer and responsive to said measuring means for correcting the vibrating amplitude of said vibrating system such that said vibrating system vibrates at a predetermined amplitude of vibration required for operation.

6. Apparatus according to claim 5 wherein said correcting means corrects the vibrating frequency of said vibrating system to thereby correct said vibrating amplitude.

7. Apparatus according to claim 5 wherein said vibrating system further includes a load detector for measuring the plug load and for adjusting the relative positions of said die and plug as a function of the output of said load detector.

8. Apparatus according to claim 5 wherein said vibration source includes a plurality of said vibration transducers and wherein said means for changing the direction of said vibratory energy includes means for combining the vibration energy of said transducers, thereby providing an output vibration energy which is substantially the sum of the energies of each of said vibration transducers.

9. Apparatus according to claim 81 wherein said vibration source includes a plurality of said transducers coupled to the periphery of a disc-shaped member, the face of said discshaped member being perpendicular to the longitudinal direction of said rod-like means.

10. Apparatus according to claim 9 wherein said vibration source includes a plurality of said disc-shaped members and transducers coupled thereto, each of said disc-shaped members being spaced M2, where A is the wavelength corresponding to the predetermined frequency of vibration of said vibrating system.

i i all 

1. A method of cold drawing metal tubes by applying vibrating energy to a plug comprising the steps of: drawing a tube through a die and over a plug which is cooperatively located with respect to said die; coupling said plug to a source of vibrations to thereby form a vibrating system; generating in said source of vibrations vibratory energy directed substantially perpendicular to the direction of drawing said tube and changing the direction of said vibrating energy by 90* to direct said energy in the direction of drawing said tube; measuring the vibrating amplitude of said vibrating system; generating a correction signal when said vibrating amplitude deviatEs from a predetermined value required for operation; and coupling said correction signal to said source of vibrations to change the vibrating amplitude of said vibrating system to said predetermined value required for operation.
 2. The method of claim 1 wherein said source of vibrations includes at least one vibration transducer generating vibrational energy in said direction substantially perpendicular to the direction of drawing said plug, and wherein said correction signal is coupled to said at least one vibration transducer to change the vibrating frequency thereof.
 3. The method of claim 2 wherein said source vibrations includes a plurality of said transducers spaced around the periphery of a disc-shaped member which has its plane substantially perpendicular to said direction of drawing.
 4. The method of claim 1 including the step of measuring the plug load, and adjusting the relative positions of said die and plug as a function of said plug load.
 5. Apparatus for cold drawing metal tubes comprising: a die through which a tube is drawn; a plug around which said tube is drawn, said plug cooperating with said die; a vibration source; rod-like means coupling said vibration source to said plug, the longitudinal axis of said rod-like means being substantially in the direction of drawing of said tube, said rod-like means; said plug and said vibration source comprising a vibrating system; said vibration source comprising at least one vibration transducer generating vibratory energy in a direction substantially perpendicular to the longitudinal axis of said rod-like means, and means for changing the direction of said vibratory energy by 90*, whereby the resulting vibratory energy is in the direction of the longitudinal axis of said rod-like means; means coupled to said vibrating system for measuring the amplitude of vibrations thereof; and means coupled to said at least one transducer and responsive to said measuring means for correcting the vibrating amplitude of said vibrating system such that said vibrating system vibrates at a predetermined amplitude of vibration required for operation.
 6. Apparatus according to claim 5 wherein said correcting means corrects the vibrating frequency of said vibrating system to thereby correct said vibrating amplitude.
 7. Apparatus according to claim 5 wherein said vibrating system further includes a load detector for measuring the plug load and for adjusting the relative positions of said die and plug as a function of the output of said load detector.
 8. Apparatus according to claim 5 wherein said vibration source includes a plurality of said vibration transducers and wherein said means for changing the direction of said vibratory energy includes means for combining the vibration energy of said transducers, thereby providing an output vibration energy which is substantially the sum of the energies of each of said vibration transducers.
 9. Apparatus according to claim 8 wherein said vibration source includes a plurality of said transducers coupled to the periphery of a disc-shaped member, the face of said disc-shaped member being perpendicular to the longitudinal direction of said rod-like means.
 10. Apparatus according to claim 9 wherein said vibration source includes a plurality of said disc-shaped members and transducers coupled thereto, each of said disc-shaped members being spaced lambda /2, where lambda is the wavelength corresponding to the predetermined frequency of vibration of said vibrating system. 